Cedar Rapids has become the speed trap of the Midwest.

Ever since installing hidden cameras on the interstate that runs through it, Iowa's second-largest city has been sending out tickets at an unprecedented rate, including to thousands of Minnesotans.

Darrell Peterson, of Savage, got nailed twice in one day last August, when he and his wife dropped their kids off with grandparents.

"It was literally a half hour apart," Peterson said. "If there were signs saying the technology was in place, I certainly didn't see them."

Peterson received two letters from the city of Cedar Rapids on the same day. Inside each was a photo of his Hyundai Sonata and an order to pay a civil fine of $75. He thought at first the city had mistakenly sent an extra citation, but when he looked closer he saw that in one photo his kids were in the car and in the other they were not.

"They got us going both ways!" Peterson said. "I've got no issue with the violations. If we were speeding, we were speeding. My issue is with the enforcement methodology."

Iowa is the only state where cities post speed cameras on interstates, and no Iowa town has embraced photo enforcement of its expressway speed limit as wholeheartedly as Cedar Rapids, a city of 128,000 halfway between the Twin Cities and St. Louis.

But the system is under fire from Iowa transportation officials, who question the safety rationale behind it.

In 2010, Cedar Rapids installed four sets of cameras on Interstate 380. Over a 20-month period in 2013 and 2014, Cedar Rapids cited more than 160,000 motorists for speeding on the interstate through town, including 16,537 from Minnesota.

That rate of 8,000 a month is well above the roughly 6,000 speeding citations law officers in Hennepin and Ramsey counties issue each month.

Minnesota is one of 38 states that don't allow speed cameras. Minneapolis tried red-light cameras in 2005 and 2006, but the state Supreme Court ruled the city had no authority to install them.

Interstate 380 is a common route for Minnesota drivers coming and going from points southeast. The raised expressway swerves through downtown Cedar Rapids in an "S" shape, around the Quaker Oats factory that smells like Cap'n Crunch, over the Cedar River, and south to Iowa City where it crosses Interstate 80.

The speed cameras, two north of the curve and two to the south, are owned and operated by Gatso USA on the city's behalf. The firm gets $25 from every $75 fine. The cameras snap a picture of any vehicle traveling at least 12 miles per hour over the speed limit and capture license plate data. The owner is then sent a citation.

Car rental companies get a lot of mail from the city of Cedar Rapids. An Enterprise Holdings center in Tulsa, Okla., received nearly 4,000 citations in the 20 months from January 2013 to August 2014. Officials at Enterprise, which also owns the Alamo and National rental brands, declined to comment.

About 70 percent of people who get a speeding citation in the mail from Cedar Rapids end up paying, according to the city. That yields about $3 million for Cedar Rapids, which assigns it to the police department, and amounts to 14 percent of the agency's fiscal 2015 budget.

The city's rationale for the cameras is that the S-curve can be dangerous, especially for unfamiliar drivers going too fast.

In 2008, a tractor-trailer driver from Texas veered on the curve to miss a car and toppled over the guardrail, said Linn County Sheriff Brian Gardner, who was outside at the time and saw it happen.

The cab disconnected from the trailer, fell nearly 40 feet and slammed to the ground in a cloud of smoke. The driver was wearing a seat belt and survived. Gardner, who has no authority over the city's speed cameras, said the wreck illustrated the dangers of the curve.

Accidents and injuries have been less common since the cameras went up and there have been no deaths, data shows. Three people were killed in crashes on the stretch in 2008 and 2009, compared to none in 2012 and 2013.

"It's my professional and personal opinion that the speed cameras have made the S-curve through downtown Cedar Rapids safer for drivers," Gardner said.

Camera removal ordered

The Iowa Department of Transportation (DOT), after a review of all traffic cameras in the state, in March ordered Cedar Rapids to remove two of the four sets of cameras and move the other two.

Most speeders nabbed on the interstate in Cedar Rapids — 94 percent overall in 2013 — are caught by the cameras at the J Avenue underpass just north of the S-curve. The cameras pointed at the northbound lanes there should be removed, the DOT said, since drivers by then are already past the danger of the S curve.

The J Avenue cameras in the southbound lanes, which catch the most speeders of all, must be moved farther south, closer to the beginning of the curve, the DOT said. They are 896 feet from the sign that drops the speed limit to 55 mph, which is also posted with a "photo enforced" sign. That's too close, said Steve Gent, director of traffic and safety for the Iowa DOT.

"A thousand feet goes by really quick when you're driving," Gent said. "It's critical that the public believe these cameras are about safety."

The city appealed, saying if motorists know there will only be a speed camera just before they hit the curve, they'll speed up after they pass it, defeating the purpose of the system. "There are no disadvantages to the current … program, other than displeasure among violators," the city wrote.

The DOT is scheduled to answer the appeal by May 16.

Hard lesson learned

Nancy Holden, a retired schoolteacher from North Mankato, never got in trouble for speeding in her life until she ran the J Avenue gantlet in Cedar Rapids. She and her husband were driving to Washington, D.C., to visit their daughter's family, which they do regularly.

They prefer the route through Cedar Rapids because it lets them avoid Chicago, and they drove through in late August.

When the letter from Cedar Rapids showed up in her mailbox, Holden was mystified.

"That was the first ticket I've ever had, and I'm 75 years old," she said.

She paid. It didn't seem worth it to argue. The Holdens still struggle to locate the speed cameras that nailed them — they're concealed behind signs. But now they are extra cautious.

"Believe me, now I slow down pretty early," Holden said. "It makes me a little nervous to be there."

Adam Belz • 612-673-4405 Twitter: @adambelz